McDATA StorageWorks 2/140 - Director Switch Planning Manual page 111

ATTENTION ! Activating a preferred path can result in receipt of out-of-
order frames if the preferred path differs from the current path, if input and
output (I/O) is active from the source port, and if congestion is present on the
current path.
A rerouting delay parameter can be enabled at the Element
Manager application to ensure a director or switch provides
correct frame order delivery. The delay period is equal to the error
detect time out value (E_D_TOV) specified in the Element
Manager application. Class 2 frames transmitted into the fabric
during this delay period are rejected; Class 3 frames are discarded
without notification. By default, the rerouting delay parameter is
disabled.
NOTE: To prevent E_Port segmentation, the same E_D_TOV and
resource allocation time out value (R_A_TOV) must be specified for each
fabric element.
• E_Port segmentation - When an ISL activates, the two fabric
elements exchange operating parameters to determine if they are
compatible and can join to form a single fabric. If the elements are
incompatible, the connecting E_Port at each director or switch
segments to prevent the creation of a single fabric. A segmented
link transmits only Class F traffic; the link does not transmit Class
2 or Class 3 traffic. The following conditions cause E_Ports to
segment:
— Incompatible operating parameters - Either the R_A_TOV or
E_D_TOV is inconsistent between the two fabric elements.
— Duplicate Domain_IDs - One or more Domain_ID conflicts
are detected.
— Incompatible zoning configurations - Zoning configurations
for the two fabric elements are not compatible. For an
explanation, refer to
— Build fabric protocol error - A protocol error is detected
during the process of forming the fabric.
— No principal switch - No director or switch in the fabric is
capable of becoming the principal switch.
Planning Considerations for Fibre Channel Topologies
Planning Considerations for Fibre Channel Topologies
Configuring Zones.
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